U.S. patent number 9,025,280 [Application Number 14/193,446] was granted by the patent office on 2015-05-05 for pmr writer device with multi-level tapered write pole.
This patent grant is currently assigned to Headway Technologies, Inc.. The grantee listed for this patent is Headway Technologies, Inc.. Invention is credited to Zhigang Bai, Moris Dovek, Kowang Liu, Yan Wu.
United States Patent |
9,025,280 |
Bai , et al. |
May 5, 2015 |
PMR writer device with multi-level tapered write pole
Abstract
A perpendicular magnetic recording (PMR) head is fabricated with
a multi-level tapered write pole. The write pole comprises a main
pole with a tapered tip on a leading edge or a trailing edge, on
which is formed at least one yoke that has a tapered edge. The edge
of the yoke is recessed from the ABS of the main pole, giving the
head a stepped profile. The yoke can be a single yoke formed on one
side of the main pole or it can be two yokes formed on both the
leading and trailing sides of the main pole. The write pole
structure creates an efficient channeling of magnetic flux to the
ABS surface of the pole tip which produces magnetic recording field
at high area densities.
Inventors: |
Bai; Zhigang (Milpitas, CA),
Liu; Kowang (Fremont, CA), Wu; Yan (Cupertino, CA),
Dovek; Moris (San Jose, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Headway Technologies, Inc. |
Milpitas |
CA |
US |
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Assignee: |
Headway Technologies, Inc.
(Milpitas, CA)
|
Family
ID: |
43030168 |
Appl.
No.: |
14/193,446 |
Filed: |
February 28, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20140177103 A1 |
Jun 26, 2014 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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13608321 |
Sep 10, 2012 |
8670212 |
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12387534 |
May 4, 2009 |
8264792 |
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Current U.S.
Class: |
360/125.15;
360/125.12; 360/125.07 |
Current CPC
Class: |
G11B
5/1278 (20130101); G11B 5/3183 (20130101); G11B
5/3163 (20130101); G11B 5/315 (20130101); G11B
5/3186 (20130101); G11B 5/398 (20130101); G11B
5/3116 (20130101); Y10T 29/49048 (20150115); Y10T
29/49041 (20150115); Y10T 29/49044 (20150115); Y10T
29/49032 (20150115) |
Current International
Class: |
G11B
5/31 (20060101) |
Field of
Search: |
;360/125.02,125.03,125.06,125.07,125.11,125.12,125.15 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Renner; Craig A.
Attorney, Agent or Firm: Saile Ackerman LLC Ackerman;
Stephen B.
Parent Case Text
This is a Divisional application of U.S. patent application Ser.
No. 13/608,321 filed on Sep. 10, 2012, which is itself a Divisional
application of U.S. patent application Ser. No. 12/387,534, filed
on May 4, 2009, now issued as U.S. Pat. No. 8,264,792 which is
herein incorporated by reference in its entirety and assigned to a
common assignee.
Claims
What is claimed is:
1. A PMR head comprising: a main pole having a trailing edge
surface and a leading edge surface and having a 1.sup.st taper on
either said trailing edge surface or on said leading edge surface,
wherein said 1.sup.st taper is defined by a region of increasing
main pole thickness in a positive y-direction away from an ABS edge
of said main pole, wherein said ABS edge is flat and wherein said
taper terminates and said main pole has a region of constant main
pole thickness extending in said positive y-direction thereafter;
and first and second tapered yokes, each having a 2.sup.nd taper,
wherein said first tapered yoke is a bottom yoke formed conformally
on said leading edge surface of said region of constant main pole
thickness of said main pole, wherein said 2.sup.nd taper of said
bottom yoke is directed towards a leading edge surface of said
bottom yoke and is defined by a region of increasing first yoke
thickness of said first yoke in said positive y-direction, said
region of increasing first yoke thickness beginning at a first yoke
edge closest to said ABS edge of said main pole and increasing in a
direction away from said ABS edge until said region of increasing
first yoke thickness becomes a region of constant first yoke
thickness thereafter; and wherein said second tapered yoke is a top
yoke formed on said trailing edge surface of said region of
constant thickness of said main pole and wherein said 2.sup.nd
taper of said top yoke is marked by a slope towards a trailing edge
surface of said top yoke and a corresponding increasing second yoke
thickness in a positive y-direction wherein said increasing second
yoke thickness begins at a second yoke edge of said second yoke
closest to said ABS edge; wherein said first and second yoke edges
closest to said ABS edge of said main pole contact said region of
constant main pole thickness of said main pole and are recessed a
distance from said ABS edge.
2. The PMR head of claim 1 wherein said recessed distance of said
first and second yokes is between approximately 0.3 and 1.0 microns
between said flat ABS edge of said main pole and a respective said
yoke edge closest to said ABS edge of said main pole.
3. The PMR head of claim 1 wherein each said yoke edge closest to
said ABS edge of said main pole is characterized by a face that is
parallel to said ABS edge of said main pole and wherein said face
extends perpendicularly from said main pole to a height greater
than 0 to approximately 0.2 microns.
4. The PMR head of claim 1 wherein said 1.sup.st taper is
characterized by an upward slope towards said trailing edge surface
of said main pole.
5. The PMR head of claim 1 wherein said 1.sup.st taper is
characterized by a downward slope towards said leading edge surface
of said main pole.
6. The PMR head of claim 1 wherein said top yoke and said bottom
yoke are formed as double layers, wherein said top yoke is a first
top yoke layer having the 2.sup.nd taper and an untapered region of
constant thickness projecting in a positive y-direction thereafter
on which is formed a second top yoke layer, recessed from said
first top yoke layer and having a 3.sup.rd taper and wherein said
bottom yoke is a first bottom yoke layer having the 2.sup.nd taper
and an untapered region of constant thickness projecting in a
positive y-direction thereafter on which is formed a second bottom
yoke layer, recessed from said first bottom yoke layer having a
3.sup.rd taper and wherein said first top yoke layer is formed on a
trailing edge surface of said main pole and is recessed from said
ABS edge of said main pole and wherein said first bottom yoke layer
is formed on a leading edge surface of said main pole and
positioned symmetrically to said first top yoke layer and wherein
said second bottom yoke layer is positioned symmetrically to said
second top yoke layer.
7. The PMR head of claim 1 wherein said main pole, said top yoke
and said bottom yoke are formed by plating or sputtering alloys of
Fe and Co.
8. The PMR head of claim 1 further including a magnetic shield
formed as a trailing shield, or formed as a trailing shield and two
laterally disposed side shields or formed as a four sided shield
having a leading shield portion, a trailing shield portion and two
laterally disposed side shields and wherein said shields are formed
of a material and of a size as not to saturate with a magnetic
writing field produced by the head.
9. A PMR head comprising: a main pole having a trailing edge
surface and a leading edge surface and having a 1.sup.st taper
formed symmetrically about a mid-line on both said trailing edge
surface and on said leading edge surface, wherein said 1.sup.st
taper is defined by a region of increasing main pole thickness in a
positive y-direction away from an ABS edge of said main pole,
wherein said ABS edge is flat and wherein said taper terminates and
said main pole has a region of constant main pole thickness
extending in said positive y-direction thereafter to a point of
termination; a pair of tapered yokes, each having a 2.sup.nd taper,
stitched symmetrically on said leading edge surface and said
trailing edge surface of said region of constant main pole
thickness of said main pole and extending in a positive y-direction
beyond said main pole, wherein said 2.sup.nd taper of each yoke is
directed towards said main pole and is defined by a region of
increasing yoke thickness of said yoke in said positive
y-direction, said region of increasing yoke thickness beginning at
a yoke edge closest to said ABS edge of said main pole and
increasing in a direction away from said ABS edge until said region
of increasing yoke thickness becomes a region of constant yoke
thickness thereafter and wherein said region of constant yoke
thickness extends beyond the termination point of said main pole;
and wherein said yoke edge closest to said ABS edge of said main
pole contacts said region of constant main pole thickness of said
main pole and is recessed a distance from said ABS edge.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to magnetic recording heads,
particularly to perpendicular recording heads that produce
recording magnetic fields that are substantially perpendicular to
the recording medium. More specifically, the invention relates to a
tapered shape of a magnetic pole of a recording head that allows a
more efficient delivery of a magnetic recording field to a
recording medium.
2. Description of the Related Art
The increasing need for high recording area densities (up to 500
Gb/in.sup.2) is making the perpendicular magnetic recording head
(PMR head) a replacement of choice for the longitudinal magnetic
recording head (LMR head).
By means of fringing magnetic fields that extend between two
emerging pole pieces, longitudinal recording heads form small
magnetic domains within the surface plane of the magnetic medium
(hard disk). As recorded area densities increase, these domains
must correspondingly decrease in size, eventually permitting
destabilizing thermal effects to become stronger than the magnetic
interactions that tend to stabilize the domain formations. This
occurrence is the so-called superparamagnetic limit.
Recording media that accept perpendicular magnetic recording, allow
domain structures within a magnetic layer to be formed with a
perpendicular orientation relative to the disk surface, while a
soft magnetic underlayer (SUL) formed beneath the magnetic layer
acts as a stabilizing influence on these perpendicular domain
structures and also serves to channel a return flux back to the
head to strengthen the recording field. Thus, a magnetic recording
head that produces a field capable of forming domains perpendicular
to a disk surface, when used in conjunction with such perpendicular
recording media, is able to produce a stable recording with a much
higher area density than is possible using standard longitudinal
recording.
Although the magnetic media used in conjunction with perpendicular
writing are capable of storing a high area density, the write head
itself must be able to produce magnetic fields of sufficient
intensity and definition to make use of the media's capabilities.
One approach to matching the writer capabilities to those of the
media is to fabricate a tapered magnetic pole tip. Such a design
presents a smaller footprint where it emerges at the ABS, yet
delivers more flux. U.S. Pat. No. 7,322,095 and U.S. Patent
Applications 2008/0112082 and 2005/0237665 (Guan et al.) show such
a main pole tapered preferably at its trailing edge and shielded on
four sides.
Traditionally, a top yoke (TY), a bottom yoke (BY) or both have
been used in PMR writers to deliver flux to the main pole. As a
consequence, these yokes are often referred to as auxiliary poles.
Referring to FIGS. 1a-1b, there are shown the following prior art
arrangements.
FIG. 1a shows a highly schematic diagram of a side view of a PMR
single pole (14) writer positioned above a moving magnetic media
(16). The media is moving in the direction of the arrow (180). The
term "leading edge" (indicated in the figure by the legend "Leading
Edge") of the writer or its various elements refers to the edge or
surface into which the disk is moving. Typically, the read head,
which is not shown here, would be formed on the leading edge side
of the writer, so an area on the disk moves past the reader before
passing beneath the writer. Where a figure does not indicate a disk
or a reader, the notation of leading or trailing will be indicated
by a legend. For consistency of description, a set of x, y, z axes
define directions in this and remaining figures that display a PMR
writer. The positive y-direction is away from the ABS of the
writer. The x-direction defines the thickness direction of the pole
layer (14) and the yoke layer (17) (i.e. the direction of layer
formation by plating or the like). The positive z-direction (circle
with a central dot) is out of the figure plane.
The main pole of this writer (14) consists of flared portion (11),
which will be more clearly shown in FIG. 1b, and a narrow pole tip
(13), which extends from the flared portion and presents an exposed
ABS shape (19) just above the media (16). The writer has a return
pole (15), that completes a magnetic flux loop (not shown), out
from the main pole, through the media soft underlayer, back up
through the return pole (15) and around through a bottom yoke (17)
(formed beneath the pole) to which the pole tip is attached. A
single exemplary current carrying coil winding (12) is shown as
wrapped around the yoke (17) and represents the mechanism by which
a magnetic field is generated. The ABS surface of the writer is
indicated by the dashed line with the legend "ABS". The main pole
(14), in this configuration, is mounted on the leading edge surface
of the bottom yoke (17).
Referring next to FIG. 1b there is shown, schematically, a top view
of the main pole (14) and pole tip (13), as it would appear if
viewed along the thickness direction of the writer, or the arrow
(180), or the x-axis of FIG. 1a. Note, as discussed above, that the
main pole (14) generally has a horizontal shape that includes a
small rectangular portion (13) and a triangular flaring portion
(11). The pole tip projects from the narrow portion of (11). The
ABS surface (19) of the pole tip (13) has a width, w, and the pole
tip itself has neck height NH, defined by its length before the
taper if the pole tip is reached.
Referring now to FIGS. 2a, 2b and 2c, there are shown three
possible approaches to channeling magnetic flux from a yoke to a
main pole, any of which could be applied to the configuration of
FIG. 1a. In FIG. 2a, there is schematically shown the main pole
(14) attached beneath the yoke (17a), which thereby acts as a top
yoke. Typically, the distance, d, between the perpendicular edge of
the yoke (18a) and the tip of the pole (19) is approximately 1.5
microns or greater.
In FIG. 2b, there is schematically shown the same main pole (14),
with the yoke (17b) now serving as a bottom yoke and the same
approximate 1.5 micron or greater distance between the yoke edge
(18b) and the pole tip.
In FIG. 2c, there is shown a main pole configuration in which the
main pole is sandwiched between a top (17a) and bottom (17b)
yoke.
Referring finally to FIG. 2d, there is shown a top view of the
configuration in FIG. 2c, in which the main pole (14) is shown
projecting from between the top and bottom yokes (17a)/(17b). Note,
this figure would appear substantially the same if it were used to
illustrate the configurations of FIGS. 2a or 2b, the difference
being that only one yoke (17a) or (17b) would be seen.
Along with the above cited methods of attaching a pole tip to a top
yoke, a bottom yoke or both, the tip itself may be provided with a
tapering profile just above its emergence at the ABS of the writer.
Referring to FIGS. 3a, 3b and 3c, there are shown three pole tips
with trailing edge, leading edge and both leading and trailing
edge, tapers. Note that a trailing (leading) taper refers to a
bevel (reduction in thickness) that begins at the trailing
(leading) edge face of the pole tip, a distance away from the ABS
(shown as a dashed line) and produces a diminishing thickness
towards the ABS face of the pole tip, at which point the bevel
stops.
The methods by which the pole tip is tapered and the general design
of the taper are also taught in the following patents and published
applications.
U.S. Patent Application 2005/0219743 (Guan et al--Headway)
discloses that the main pole may be tapered at the leading or the
trailing edge.
U.S. Pat. No. 7,133,252 (Takano et al) shows that the main pole may
be tapered at the leading edge or the trailing edge or both.
U.S. Pat. No. 5,600,519 (Heim et al) discloses a tapered pole
tip.
U.S. Patent Application 2008/0316653 (Sasaki et al). FIG. 12 shows
the pole tapered and the nonmagnetic layer 17 also tapered.
SUMMARY OF THE INVENTION
A first object of this invention is to provide a pole structure for
a perpendicular magnetic recording (PMR) writer capable of
recording at high area densities.
A second object of the present invention is to provide such a pole
structure for a perpendicular magnetic recording head in which the
write magnetic field is increased by means of more efficient
provision of magnetic flux to the ABS of the pole tip.
A third object of the present invention is to provide a PMR writer
with enhanced writing capabilities at narrow track widths.
A fourth object of the present invention is to provide a PMR writer
with improved field gradient and other performance enhancements
provided by improved writing capabilities.
A fifth object of the present invention is to provide such a PMR
writer with a shielded pole structure so that writing to adjacent
tracks is eliminated.
The objects of the present invention are realized by the formation
of a write pole with multi-level tapering in the direction
perpendicular to the air bearing surface (ABS). The taper is
applied to both the pole tip (called the 1.sup.st taper) and to the
edges of the yoke structures, which can be above or below the pole
tip, to which the pole tip is attached (called the 2.sup.nd
taper).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a is a schematic representation of side view of an exemplary
prior art PMR having a single main pole.
FIG. 1b is a schematic top view of the same PMR showing the shape
of the main pole.
FIGS. 2a, 2b and 2c are prior art schematic representations showing
exemplary main poles attached to top (2a), bottom (2b) and top and
bottom (2c) yokes, so that the edges of the yokes are recessed from
the pole tips.
FIG. 2d is a top view of any of the configurations in FIG. 2a, 2b
or 2c.
FIGS. 3a, 3b and 3c show three prior art pole tips with tapers at
their trailing, leading and leading and trailing sides.
FIG. 4a is a schematic side cross-sectional illustration of an
embodiment of the present invention showing a multi-level tapered
main pole.
FIG. 4b is a top view of the configuration in FIG. 4a.
FIG. 5 is a graphical representation showing the on-track
performance of a PMR using the double-level tapered main pole
configuration of the current invention as compared with a reference
PMR that is shielded and has a single level of tapering but lacks
the double tapered configuration.
FIG. 6a-6f shows six schematic illustrations of side
cross-sectional views of possible combinations of top yokes and
bottom yokes with leading and trailing tapers, to which is attached
a main pole with a tip having trailing and/or leading tapers.
FIG. 7a-7c show three schematic illustrations of side
cross-sectional views of a main pole having trailing, leading and
both leading and trailing tapers, sandwiched between a top yoke
with a leading taper and a bottom yoke having a trailing taper.
FIG. 8 shows a schematic side cross-sectional view of a three-level
tapered write pole.
FIG. 9 shows a schematic side cross-sectional view of a small
double-level tapered main pole, partially sandwiched (stitched)
between an upper yoke and a lower yoke.
FIG. 10a-10d shows a view of the ABS surface the pole tip of any of
the multi-level tapered main poles of the present invention, in an
(a) unshielded configuration; (b) trailing edge shielded; (c)
trailing edge and side shielded; (d) shielded on all four
sides.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred embodiment of the present invention is a multi-level
tapered write pole structure for use within a perpendicular
magnetic recording (PMR) head. A first level of the tapering (i.e.
an increasing thickness in the layer produced by a bevel) begins at
the ABS edge of the pole tip (this is called the 1.sup.st taper)
and extends in the positive y-direction (away from the ABS). The
1.sup.st taper ends and the pole layer then retains a constant
maximum thickness from that point backwards (i.e., away from the
ABS). A second level of tapering begins at the edges of the upper
and/or lower yoke structure (2.sup.nd taper) which contacts the
pole tip on the constant thickness portion of either a top surface
or a bottom surface and proceeds in the positive y-direction until
the yoke layer attains a constant thickness.
Referring to FIG. 4a, there is shown a schematic drawing of a
side-view cross-section of a double-level tapered write pole that
is a preferred embodiment of the present invention. In this
embodiment, the main pole (14) is sandwiched between a top yoke
(17a) and a bottom yoke (17b) that are formed conformally on the
main pole on its trailing (top) and leading (bottom) surfaces
respectively. The top yoke (17a) is formed on the top surface
(trailing surface) of the main pole; the bottom yoke (17b) is
formed on the bottom surface (leading surface) of the main pole.
This particular configuration is reflection-symmetric about a z-y
mid-plane passing through the mid-line (shown as a dashed line) of
the main pole.
The taper of the main pole is defined by a region of symmetrically
(about said z-y mid-plane) increasing thickness in the direction
away from (i.e. in the positive y-direction defined in FIG. 1a))
the ABS end of the main pole (19). The taper terminates at a back
edge (21), from which edge distally backwards, the main pole
remains flat and horizontal and the thickness of the pole remains
constant as the pole extends away from the ABS. Note, the direction
away from the ABS of the pole tip may be referred to hereinafter,
with equal accuracy, as the distal direction or the positive
y-direction.
As is indicated in the drawing, the vertical front edges (18a),
(18b), of the yokes have planar faces that are parallel to the ABS
of the main pole (19) and that the second taper is formed as an
upward sloping (beveled) surface extending distally from the planar
edge face (18a) to the trailing surface of the top yoke and from
the planar edge face (18b) of the bottom yoke (17b) downward to the
leading surface of the bottom yoke. Note again that the taper of
the top yoke slopes upward from edge (18b) towards its trailing
surface, whereas the taper of the bottom yoke (17b) slopes downward
towards its leading edge. The faces of these edges (18a)/(18b) are
formed distally to the back edge (21) of the main pole taper and
are recessed from the pole tip ABS (19) by an amount between
approximately 0.3 and 1.0 microns. Thus, there is a short exposed
flat portion (23) of the top and bottom surfaces of the main pole
between the back edge of the 1.sup.st taper (21) of the pole and
the front edge of the 2.sup.nd taper (18a), (18b) of the yokes. The
height of the vertical faces of the front edges (18a), (18b) is
between approximately 0 and 0.2 microns. The increasing thickness
of the second taper in the distal (positive y) direction stops and
the yoke maintains a substantially constant thickness thereafter.
The thickness of the 2.sup.nd taper region is between approximately
0.3 to 1.0 microns. The horizontal shape of the 2.sup.nd taper
region is conformal to the shape of the flaring portion of the main
pole (14), which is generally a triangular shape as shown in FIG.
4b. The thickness of the combined layers is between approximately
0.5 and 3.0 microns and the material forming the layers is alloys
of Fe and Co as is known in the art.
It is to be noted that the front edges of the 2.sup.nd taper on the
upper and lower yokes (18a), (18b) are much closer to the ABS than
the top/bottom yokes of conventional PMR designs, which permits the
delivery of more flux to the ABS of the pole tip (19). In addition,
the conformal shape of the 2.sup.nd tapered region to the main pole
itself, produces a tapered front cross-sectional aspect which also
helps to efficiently concentrate more flux to the pole tip ABS
(19).
Referring to FIG. 4b, there is shown a top schematic view of the
yoke and main pole as would be seen looking towards the trailing
surface of the top yoke. The front edge of the 2.sup.nd taper (18a)
or (18b) is shown in outline as is the back edge of the 1.sup.st
taper (21). The triangular portion of the main pole (11) is
conformally covered by the top or bottom yoke tapered portion
(11a), if a single yoke is used, or by both yokes, if a sandwich
configuration is constructed.
It is to be noted that fabrication of the pole structure can be
understood with reference to FIG. 4b as described above. The
fabrication can be easily accomplished using the masking process as
for prior art designs with only slight modification of mask
alignment to take into account the recessing of the yokes relative
to the pole tip. In-plane alignment should not be difficult,
however, because of the fact that the recessing (distance between
(19) to (18a)) is at least 0.3 microns from the ABS, where 0.3
microns is the width of the pole.
More specifically, a tapered bottom yoke (17b) can be created first
by milling (via an ion beam etch, a RIE etch or the like) a sloped
region in an AlOx substrate having a smooth planar surface,
followed by plating or sputtering a yoke layer into the milled
region and applying CMP to form a smooth planarized surface. After
the pole (19) is formed on the planarized bottom yoke, a tapered
top yoke (17a) can be formed on the pole by plating or sputtering a
conventional (un-tapered) top yoke as defined in the prior art and
then milling the front of the yoke to create the necessary taper.
The pole is formed, also by plating or sputtering through a mask,
onto the already planarized bottom yoke. Here, the mask is aligned
over the bottom yoke to create the necessary recess of the yoke
behind the tip of the pole. Once the pole is formed, the top yoke
(17a) is formed, as noted above, on the pole, using a conventional
mask that is properly aligned to create the required recess. Once
the top yoke is formed and tapered, the pole tip can also be
tapered, again using milling or RIB as the mechanism
Referring to FIG. 5, there is shown a graphical comparison of the
multi-level tapered main pole of the present invention as shown in
FIGS. 4a and 4b with a reference writer using a single pole tip
with trailing and leading edge tapers right at the ABS. The
vertical axis measures magnetic field H.sub.y (Oe) into the
magnetic medium and the horizontal axis measures downtrack position
in cm.
The reference pole has only 1.sup.st level tapering and lacks the
tapered and recessed top and bottom yokes shown as (17a) and (17b)
in FIG. 4a. As shown in the graphs, the curve representing the
present invention (1) shows a significant improvement in peak
H.sub.y by approximately 380 Oe or approximately 4%. It is to be
noted that the significant improvement in field strength of the
present invention might make it desirable to further optimize
shield design, so that cross-track flux will be reduced.
Referring now to FIGS. 6a-6f, there are shown six schematic
cross-sectional side views of combinations of 1.sup.st (pole) and
2.sup.nd (yoke) tapers for a main pole (14) and an attached
recessed top yoke (17a) or bottom yoke (17b) that could meet the
objects of the present invention. In FIG. 6a both the 1.sup.st and
2.sup.nd tapers are trailing edge tapers. In FIG. 6b, they are,
respectively, leading and trailing edge tapers. In FIG. 6c, they
are, respectively, leading/trailing and trailing edge tapers. In
FIG. 6d, they are trailing and leading edge tapers. In FIG. 6e,
they are, respectively, leading, leading edge tapers and, finally,
in FIG. 6f they are leading/trailing and leading edge tapers.
Referring now to FIGS. 7a-7c, there are shown three schematic
cross-sectional side views of tapered poles (14), each formed
between a top (17a) and bottom (17b) tapered yoke to provide
1.sup.st and 2.sup.nd tapers. Either of these three configurations
could meet the objects of the present invention. In FIG. 7a the top
yoke (17a) has a trailing edge taper, the bottom yoke (17b) has a
leading edge taper and the main pole (14) has a trailing edge
taper. In 7b, the top and bottom yokes are the same as in 7a, but
the main pole (14) has a leading edge taper. Finally, the
configuration of FIG. 7c has a main pole (14) with a symmetric
leading/trailing edge taper.
Referring to FIG. 8, there is shown a 3-level tapered pole
comprising a main pole (14) sandwiched between a first top and
bottom yoke (171a), (171b), the entire configuration then being
sandwiched between a second top and bottom yoke (172a), (172b).
This 3-level tapered pole would also meet the objects of the
present invention and is an alternative embodiment thereof.
Referring to FIG. 9, there is shown a stitched, 2-level main pole
configuration in which a shortened main pole (14) is affixed
between two yokes (17a) and (17b). Such a stitched configuration
allows the formation of a short pole segment (14) which can be
advantageous in that the shorter segment produces stable domain
structures that persist during inactive periods when the write
current is off. Such a structure would form another embodiment of
the present invention.
Referring now to FIG. 10a-10d, there are shown four views of the
ABS of the pole tip of the present invention in different shielded
configurations. FIG. 10a shows the pole tip unshielded. FIGS.
10b-10d show the pole tip surrounded respectively by a trailing
shield (10b) a trailing shield and two side shields (10c) and a
trailing shield, a leading shield and two side shields (10d). These
embodiments are meant to illustrate the fact that shielded
configurations of the multi-level tapered pole structure are
possible using similar shield design technology of the prior art.
It is to be noted, however, that the significantly increased flux
produced by the multi-level tapered pole of this invention could
very well require that shield dimensions be re-formulated to
provide the protection against unwanted side writing at the new
levels of write field intensity. Shield structures must be formed
with sufficient volume and of proper magnetic moment materials so
that they do not saturate under the influence of the strong writing
fields produced by the present pole configurations. At present,
however, the shield designs used in testing the present invention,
such as used in generating the graphs of FIG. 4 have proven
adequate.
As is understood by a person skilled in the art, the preferred
embodiment of the present invention is illustrative of the present
invention rather than limiting of the present invention. Revisions
and modifications may be made to methods, materials, structures and
dimensions employed in forming and providing a PMR head having a
multi-level tapered main pole, while still forming and providing
such a PMR head and pole and its method of formation in accord with
the spirit and scope of the present invention as defined by the
appended claims.
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